ISSC Mk22 12" Commando Barrel?

Hi, I was just wondering if you guys can get the shorter barrel for the mk22? If so can you give some details on it? All I can find is that its out there somewhere... Does it still use a shroud or is it a real bull barrel?

Will using it make the rifle need the stock pinned for legality issues?

Only if you pin the stock so that it is no longer able to fold. Barrel length laws do not apply to rimfire rifles. Overal length laws, however, do apply. Neat fact... Barrel length laws do not count flash hiders, etc. as part of the barrel's length. Overall length laws make no such exemption.